It is easy to confuse between Do–While and Do–Until, since they both share a lot of similarities. However, the difference between them is in fact, pretty clear. The Do–While loop executes as long as the outcome of the condition check is $true, and exits the moment it becomes $false. Do–Until is the opposite: the loop continues as long as the condition check returns $false, and stops the moment it the condition check returns $true.

Let us use the same scenario of cleaning up empty folders, but this time, use the Do–Until loop.